1. Field
The present disclosed embodiments relates generally to communication, and more specifically to efficient computation of digital gains for automatic gain control.
2. Background
In a wireless communication system, a transmitter typically processes (e.g., encodes and modulates) data and generates a radio frequency (RF) modulated signal that is more suitable for transmission. The transmitter then transmits the RF modulated signal via a wireless channel to a receiver. The wireless channel distorts the transmitted signal with a channel response and further degrades the signal with noise and interference.
The receiver receives the transmitted signal, conditions the received signal to obtain a baseband signal, digitizes the baseband signal to obtain samples, and processes these digitized signals. The received signal level may vary over a wide range due to various channel propagation phenomena such as fading and shadowing. Hence, the receiver typically performs automatic gain control (AGC) to maintain the baseband signal level within an acceptable range. The AGC attempts to avoid saturation of receiver circuitry and clipping of an analog-to-digital converter (ADC) used to digitize the baseband signal.
In AGC, a variable gain amplifier (VGA) is commonly used to maintain constant signal amplitude. This VGA may be implemented as an analog variable gain amplifier (AVGA) or a digital variable gain amplifier (DVGA).
Using an AVGA has many disadvantages including, among other things, complicated circuitry for maintaining a linear-in-dB gain control characteristics, temperature compensation and considerable power consumption.
DVGAs overcome many of these disadvantages of AVGAs. However, computing and applying a digital gain for AGC is difficult.
There is therefore a need in the art for techniques to perform digital gain computation for AGC at a wireless receiver in an efficient and cost-effective manner.